Fuel Pump

ABSTRACT

A fuel pump for delivering fuel in a motor vehicle, having a side channel stage. The fuel pump further includes a peripheral stage. The peripheral stage produces the same pressure at lower volume flow across the periphery of the rotor as compared to a side channel stage. For this purpose, the cross-sections of the delivery compartments of the peripheral stage are smaller than the cross-sections of the delivery compartments of the side channel stage. The fuel pump therefore has a higher efficiency and is less susceptible to soiling.

PRIORITY CLAIM

This is a U.S. national stage of application No. PCT/EP2008/055987, filed on May 15, 2008, which claims priority to German Application No. 10 2007 026 533.8, filed on Jun. 8, 2007, the content of both incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a fuel pump for delivering fuel in a motor vehicle having a rotor that is rotatable between an inlet-side casing part and an outlet-side casing part and with a side channel stage arranged in the faces, at a distance from the outer rim, the side channel stage having delivery chambers that extend from an inlet to an outlet and which have rings, arranged in the rotor, of guide vanes that delimit vane chambers, and mutually opposite vane chambers of the side channel stage being connected to one another.

2. Prior Art

Fuel pumps of this kind are used in motor vehicles and are known in practice. The flow through the side channel stage of the known fuel pump is axial and said stage delivers fuel from the fuel tank to an internal combustion engine of the motor vehicle. The side channel stage, with the vane chambers at a distance from the outer rim of the rotor, has a high efficiency but is susceptible to the ingress of dirt particles into a gap between the rotor and casing parts, especially radially to the outside of the ring of vane chambers. These dirt particles lead to wear and hence to an enlargement of the gap between the rotor and the casing part, resulting in a loss of efficiency. As an alternative, fuel pumps that have a peripheral stage and vane chambers arranged in the radially outer rim have been disclosed. Such fuel pumps are not susceptible to soiling but have only a low efficiency.

Consideration has already been given to arranging a plurality of vane chamber rings on the rotor in order, for example, to supply a suction jet pump with fuel or to configure the delivery of fuel in two stages arranged in series. Here, a pressure gradient arises between the two vane chamber rings, and this likewise leads to the ingress of dirt into the gap between the rotor and the casing part.

SUMMARY OF THE INVENTION

An object of one embodiment of the invention is to develop a fuel pump of the type described at the outset such that wear is minimized and the pump has a high efficiency.

According to one embodiment of the invention, this problem is solved by at least one ring of guide vanes for at least one delivery chamber of a peripheral stage, said vanes delimiting vane chambers, the at least one ring of guide vanes being arranged on the outer rim of the rotor. The delivery chamber of the peripheral stage has a significantly smaller cross-section than the delivery chambers of the side channel stage, and respective inlets and outlets of the side channel stage and the peripheral stage are connected to one another.

Because the respective inlets and outlets of the side channel stage and of the peripheral stage are connected, the two stages are connected in parallel with one another. However, the majority of the delivery output of the fuel pump according to the invention is produced with high efficiency by the side channel stage. As a result, the fuel pump according to the invention is particularly efficient. Because the cross-section of the vane chambers in the peripheral stage is particularly small, this stage makes only an a slight contribution to the delivery output and serves principally to build up a counterpressure to the side channel stage in the fuel pump and to carry away dirt particles. The counterpressure to the side channel stage has the effect that the ingress of dirt particles into the gap between the rotor and the casing part is kept particularly small. The wear of the rotor and of the casing parts in the region in which they adjoin the vane chambers of the side channel stage is thereby kept particularly low.

According to an advantageous development of the invention, avoiding an accumulation of dirt in the radially outer region of the rotor is a particularly simple matter if, compared to the side channel stage, the peripheral stage is designed to produce the same pressure across the periphery of the rotor with a smaller volume flow as the side channel stage.

A particularly compact configuration by virtue of axial flow through the fuel pump according to the invention can be achieved in a simple manner if the inlet of the side channel stage is arranged in the inlet-side casing part and leads to a first face of the rotor, and if the outlet of the side channel stage is arranged in the outlet-side casing part and leads away from a second face.

The peripheral stage could, for example, be supplied with fuel via a slot leading in the inlet-side casing part to the inlet of the side channel stage. However, this leads to multiple deflection of the flow of fuel. According to another advantageous development of the invention, a further contribution to reducing turbulence in the flow of fuel is made if the inlet of the peripheral stage is arranged parallel to the inlet of the side channel stage and leads to the first face of the rotor.

According to another advantageous development of the invention, the outlay on construction required to produce an intended pressure in the peripheral stage can be kept particularly low if a spacer ring, which holds the casing parts at a distance from one another, has a guide element for producing an intended pressure gradient across the periphery of the rotor.

A contribution is made to further reducing the dimensions of the fuel pump according to one embodiment of the invention if the outlet of the peripheral stage is arranged in the spacer ring and leads radially away from the rings of vane chambers.

According to another advantageous development of the invention, an intended pressure profile across the periphery of the rotor can be established in a simple manner if the spacer ring has respective recesses at the inlet and at the outlet of the peripheral stage and between the two recesses on both faces of the rotor the peripheral stage has delivery chambers that are at least partially separated from one another. The separation between the two delivery chambers of the peripheral stage is preferably brought about by the guide element.

According to another advantageous development of the invention, a contribution to further simplifying the adjustability of the pressure profile across the periphery of the rotor is made if the spacing of an edge of the spacer ring, said edge lying opposite the encircling rim of the rotor, is greater near the inlet of the peripheral stage than close to the outlet.

A contribution to simplifying the assembly of the fuel pump according to the invention is made if a shell surrounding the casing parts and the spacer ring delimits the recess in the spacer ring radially towards the outside at the outlet.

A contribution to further reducing turbulence in the flow of the peripheral stage is made if the outlet-side casing part has a guiding edge sloping in the direction of flow at the outlet of the peripheral stage.

BRIEF DESCRIPTION OF DRAWINGS

The invention allows numerous embodiments. To further clarify its basic principle, one of these is illustrated in the drawing and is described below. In the drawings,

FIG. 1 is a partial section through a fuel pump according to one embodiment of the invention; and

FIG. 2 is an exploded view of a pump stage of the fuel pump shown in FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a fuel pump with a pump stage 2 driven by an electric motor 1. The pump stage 2 has a rotor 4 arranged in a torsionally rigid manner on a shaft 3 of the electric motor 1. The rotor 4 is arranged rotatably between two mutually opposite casing parts 5, 6. The casing parts 5, 6 are held at a distance from one another by a spacer ring 7. A shell 8 of the fuel pump preloads the casing parts 5, 6 against the spacer ring 7. The pump stage 2 has a side channel stage 9 and a peripheral stage 10. The side channel stage 9 has two mutually opposite rings of guide vanes 12 delimiting vane chambers, said rings being arranged in the rotor 4 at a distance from the radially outer rim. The peripheral stage 10 has two rings of guide vanes 14 delimiting vane chambers 13, said rings being arranged in the radially outer rim of the rotor 4. Together with respective partially annular channels 15, 16 arranged in the casing parts 5, 6, each of the vane chambers 11, 13 forms a delivery chamber 17, 18. Each of the delivery chambers 17, 18 extends from an inlet 19 to an outlet 20 of the pump stage 2. The inlet 19 is arranged in one of the casing parts 5, while the outlet 20 is arranged in the other casing part 6. As a result, there is an axial flow through the pump stage 2 and the fuel is delivered to a connection branch 21 of the fuel pump. For the sake of simplicity, the inlet 19 and the outlet 20 are shown rotated into the plane of the drawing.

The delivery chambers 18 of the peripheral stage 10 have a significantly smaller cross section than the delivery chambers 17 of the side channel stage 9. As a result, most of the fuel is delivered via the side channel stage 9.

However, the peripheral stage 10 produces the same pressure gradient and hence pressure profile across the periphery of the rotor 4, with the result that a counterpressure to the side channel stage 9 is produced. This keeps down leakage from the side channel stage 9 in the radially outer direction. Dirt particles likewise pass through the peripheral stage 10 to the outlet 20. FIG. 1 furthermore shows that the outlet-side casing part 6 has a guiding edge 22 sloping in the direction of flow at the outlet 20 of the peripheral stage 10.

In the side channel stage 9, axial guidance for the flow of fuel through the rotor 4 is provided by an overlap between the mutually opposite delivery chambers 17 in the rotor 4. In the peripheral stage 10, the flow is guided by a guide element 23 arranged on the spacer ring 7. The pressure gradient described in the peripheral stage 10 can be set precisely by the shape and dimensions of the guide element 23, these being illustrated in FIG. 2 in an exploded view of the pump stage 2. At the inlet 19 and the outlet 20 of the peripheral stage 10, the spacer ring 7 has respective recesses 24, 25 to guide the flow of fuel. The spacer ring 7 with two recesses 24, 25, separates the delivery chambers 18 of the peripheral stage 10 which are illustrated in FIG. 1.

Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto. 

1.-10. (canceled)
 11. A fuel pump configured to deliver fuel, comprising: an inlet-side casing part having a fluid inlet; an outlet-side casing part having at least one fluid outlet; a rotor which is rotatably arranged between the inlet-side casing part and the outlet-side casing part the rotor having rings of guide vanes, the rotor forming: a side channel stage having two opposite rings of the rings of the guide vanes configured to form at least one delivery chamber of the side channel stage and delimiting first vane chambers connected to one another, the two opposite rings arranged in the rotor at a distance from a radial outer rim; and a peripheral stage including at least one of the rings of guide vanes configured to form at least one delivery chamber of the peripheral stage and delimiting second vane chambers arranged on the outer rim of the rotor, wherein the delivery chamber of the peripheral stage has a smaller cross-section than the at least one delivery chamber of the side channel stage, and respective fluid inlets and fluid outlets of the side channel stage and the peripheral stage are connected to one another.
 12. The fuel pump as claimed in claim 11, wherein, the side channel stage and the peripheral stage are configured to produce a same pressure across a periphery of the rotor.
 13. The fuel pump as claimed in claim 11, wherein the fluid inlet of the side channel stage is arranged in the inlet-side casing part and leads to a first face of the rotor, and the fluid outlet of the side channel stage is arranged in the outlet-side casing part and leads away from a second face of the rotor.
 14. The fuel pump as claimed in claim 13, wherein the fluid inlet of the peripheral stage is arranged parallel to the fluid inlet of the side channel stage and leads to the first face of the rotor.
 15. The fuel pump as claimed in claim 12, further comprising a spacer ring, configured to hold the casing parts at a distance from one another, the spacer ring comprising a guide element for producing an intended pressure gradient across a periphery of the rotor.
 16. The fuel pump as claimed in claim 15, wherein the outlet of the peripheral stage is arranged in the spacer ring and leads radially away from the rings of vane chambers.
 17. The fuel pump as claimed in claim 15, wherein the spacer ring has respective recesses at the inlet and at the outlet of the peripheral stage, and between the two recesses on both faces of the rotor, the peripheral stage has delivery chambers which are at least partially separated from one another.
 18. The fuel pump as claimed in claim 15, wherein a spacing of an edge of the spacer ring opposite the encircling rim of the rotor is greater proximate the fluid inlet of the peripheral stage than proximate the fluid outlet of the peripheral stage.
 19. The fuel pump as claimed in claim 17, further comprising a shell surrounding the casing parts and the spacer rings wherein the shell delimits the recess in the spacer ring radially towards the outside at the fluid outlet.
 20. The fuel pump as claimed in claim 11, wherein the outlet-side casing part has a guiding edge sloping in the direction of flow at the outlet of the peripheral stage.
 21. The fuel pump as claimed in claim 18, wherein a shell surrounding the casing parts and the spacer ring delimits the recess in the spacer ring radially towards the outside at the outlet.
 22. The fuel pump as claimed in claim 12, wherein the peripheral channel stage produces the same pressure with a smaller volume flow than the side channel stage.
 23. A fuel pump configured to deliver fuel, comprising: a first casing part having at least one fuel inlet; a second casing part comprising: a first fuel outlet arranged at a distance radially from an outer rim of the second casing part; and a second fuel outlet arranged at the outer rim of the second casing part; a side channel stage comprising: a rotor having two mutually opposite rings of first guide vanes delimiting first vane chambers, the two mutually opposite rings of first guide vanes arranged at a distance radially from an outer rim of the rotor; and respective partially annular channels arranged in the first and second casing parts, configured to form at least one side channel delivery chamber having a first cross section, the side channel delivery chamber extending from the fuel inlet to the first fuel outlet; and a peripheral stage comprising: the rotor further comprising two peripheral rings of second guide vanes delimiting second vane chambers, the peripheral rings being arranged in the outer rim of the rotor; and respective channels arranged in the first and second casing parts, configured to form at least one peripheral stage delivery chamber having a second cross section extending from the fuel inlet to the second fuel outlet.
 24. The fuel pump as claimed in claim 23, wherein the second delivery chamber cross section is smaller than the first delivery chamber cross section.
 25. The fuel pump as claimed in claim 24, further comprising a spacer ring configured to space the first and second casing parts from one another.
 26. The fuel pump as claimed in claim 25, wherein the peripheral stage includes two peripheral stage delivery chambers, wherein the spacer ring has at least one guide configured to separate the peripheral stage delivery chambers. 